1. Field
The present disclosure relates to thermoplastic resin compositions and molded articles made from the thermoplastic resin compositions.
2. Description of the Related Art
Interest in biodegradable resins, such as aliphatic polyesters, has increased in view of environmental protection. A polylactic acid (or polylactide), which is inexpensive among the biodegradable resins, is prepared from renewable resources such as plants, has significantly lower greenhouse gas emissions than petroleum-based plastics due to biodegradation by microorganisms, and has been used for various applications such as disposable products and medical supplies requiring biodegradability.
A polylactic acid has very high rigidity at room temperature, but thermal deformation may easily occur at a temperature of about 50° C. or more and its mechanical properties are poor, for example, it is easily broken even by low impact physical events. Thus, there is a need to improve the mechanical properties of the polylactic acid.
In order to improve the mechanical properties of the polylactic acid, different types of polymers may be mixed with the polylactic acid, or a low molecular weight organic compound or inorganic particles may be added to the polylactic acid. For example, in a case where a D-type polylactic acid is added to an L-type polylactic acid, heat resistance of the polylactic acid is improved but impact resistance (i.e., resistance to changes that occur as the result of physical events) is not improved at all. In a case where a mineral, such as silica, is added to the polylactic acid, since the interaction with the polylactic acid is insufficient, and thus the effect of improving physical properties is not significant.
Therefore, there is a need to develop a method capable of simultaneously improving the mechanical impact resistance and heat resistance of the polylactic acid.